There is a conventionally known wireless communication system that collects data from wireless terminals by using wireless ad hoc networks. For example, a system that collects meter read data is used by arranging wireless terminals in meter read meters that read electrical power used in homes.
Because such wireless terminals are usually arranged in a fixed manner, the wireless terminals learn path information by using a proactive-type routing protocol. Specifically, by periodically sending and receiving a control message between adjacent terminals connected by a single hop, the wireless terminals measure the quality of paths between nodes and retain, in their own routing table, multiple paths to the final destination in descending order of the quality of the paths. In recent years, because memory saving for wireless terminals is improved, the upper limit of the number of entries that can be registered in the routing table is set.
Patent Document 1: Japanese Laid-open Patent Publication No. 10-93608
Patent Document 2: Japanese Laid-open Patent Publication No. 2010-232967
Patent Document 3: Japanese Laid-open Patent Publication No. 2011-097458
However, with the technology described above, when an entry needs to be updates, because the upper limit of the number of entries in the routing table is set, a path that is frequently used may sometimes not able to be retained due to the update of the entry. Consequently, in some cases, communication disconnection may possibly occur.